Acoustic projectors are commonly used as a part of SOund Navigation And Ranging (SONAR) system. Pulses of sound from acoustic projectors are used to probe the sea, and the echoes are then processed to extract information about the sea, its boundaries and submerged objects. In order to properly test such acoustic projectors it is critical to evaluate their performance under water. While equipment testing on an actual host platform at operational depths provides the most accurate test data, the inability to make changes to the equipment, prohibitive costs, and huge labor investments associated with this style of testing make it impracticable. To circumvent these limitations, traditional testing methods include either shallow water testing, or testing in an acoustic pressure tank.
Traditional shallow water testing involves submerging the acoustic projectors to a shallow depth, typically less than 50 feet, and testing them at various levels of power transmission. Unfortunately, operating acoustic projectors at full power in these shallow depths causes cavitation at some frequencies and can therefore cause damage to the unit under test.
As a result, acoustic pressure tank facilities are typically necessary for performing acoustic measurements at full power transmit. These facilities allow testing at varying simulated depths and usually provide robust testing equipment. However, acoustic pressure tanks require large, heavy structures as well as expensive facilities. Accordingly, there are few of these tanks available. Most are owned by the government, are difficult to schedule, expensive to rent, and require transport of equipment and travel to the facility.
A need therefore exists for a relatively low cost acoustic projector testing system capable of simulating a variety of depths and suitable for testing at full power transmission.